Two aromatic plants native to central Argentina, known locally as poleo and peperina, are quietly emerging as serious contenders in the global search for greener food preservatives. In a new study published in Discover Green Chemistry, researchers at the National University of Córdoba and CONICET report that essential oils extracted from Lippia turbinata and Minthostachys mollis can protect sunflower oil from oxidative spoilage more effectively than butylated hydroxytoluene (BHT), the petroleum-derived synthetic antioxidant that dominates the food industry. Under accelerated storage conditions designed to mimic the stresses that degrade lipid-rich foods on supermarket shelves, the two plant oils extended the shelf life of sunflower oil by more than four and nearly five and a half times respectively, compared with 3.92 times for BHT applied at its maximum legally permitted concentration.
The findings matter because lipid oxidation is one of the principal engines of food waste worldwide. When oxygen attacks the unsaturated fatty acids in oils, nuts and other lipid-containing products, it generates peroxides, aldehydes and off-flavours that render food unpalatable and, in some cases, unsafe. Food loss on this scale ripples outward, placing pressure on natural resources, raising energy consumption for distribution and storage, and driving up prices in ways that undermine food security. The global antioxidant market, valued at roughly 4.6 billion dollars in 2022 and projected to reach 7.6 billion dollars by 2032, is built largely on synthetic compounds such as BHT, BHA and TBHQ, all derived from non-renewable petrochemical feedstocks. These additives persist in the environment because of their low degradability, and their accumulating presence in processed foods has raised concerns about cumulative consumer exposure.
Essential oils offer an alternative that aligns with what the researchers describe as the e3 concept: energy efficiency, environmental sustainability and the recovery of natural additives. Unlike synthetic antioxidants, they are biodegradable, can be produced from intensively cultivated aromatic crops rather than wild harvesting, and require fewer energy inputs and no organic solvents when obtained by hydrodistillation. In the study, leaves of both species were harvested in April 2025 at the peak of flowering from the university’s experimental field in Córdoba, dried at 25 degrees Celsius, and subjected to hydrodistillation in a Clevenger-type apparatus for 60 minutes. The resulting oils were obtained in yields of 1.78 percent for Lippia turbinata and 1.96 percent for Minthostachys mollis, then analysed by gas chromatography coupled with mass spectrometry.
The chemical portraits of the two oils differ markedly. Lippia turbinata essential oil is dominated by thujone at 67.38 percent of the total composition, followed by beta-pinene at 8.52 percent and limonene at 6.51 percent, with these three compounds accounting for more than 82 percent of the oil. Minthostachys mollis oil, by contrast, is built around menthone at 51.83 percent, pulegone at 31.78 percent and isomenthone at 3.23 percent, together representing nearly 87 percent of the mixture. Neither oil is rich in the phenolic terpenes, such as carvacrol or thymol, that are conventionally associated with strong antioxidant behaviour. This makes the performance of both oils all the more intriguing, because their principal constituents act through a different and complementary antioxidant mechanism.
Phenolic antioxidants function as chain-breaking antioxidants: they donate a hydrogen atom to lipid radicals and peroxidised lipid radicals, halting the propagation of the auto-oxidation cascade. Non-phenolic terpenes such as thujone, pinene, menthone and pulegone operate as termination-enhancing antioxidants. These molecules oxidise alongside the lipids themselves, generating relatively stable radical species that pair rapidly with other radicals to form non-reactive adducts, thereby accelerating the termination reactions that remove highly reactive intermediates from the system. In the DPPH free radical scavenging assay, Minthostachys mollis oil inhibited 34.49 percent of the radical while Lippia turbinata inhibited 5.37 percent, and both oils showed total phenolic contents of roughly 8.5 to 9.1 micrograms per millilitre of gallic acid equivalents. The team cautions that such indirect tests correlate poorly with real performance in foods, partly because the polar DPPH radical interacts inefficiently with hydrophobic terpenes, which is precisely why the researchers pushed on to direct oxidation experiments in an actual food matrix.
Before testing antioxidant power, the team examined how well the oils withstand heat, since an antioxidant that decomposes during storage or processing loses its value. Aliquots of each oil were held at 60 degrees Celsius for 28 days in sealed vials, with their volatile profiles captured by solid-phase micro-extraction and analysed at five time points. Principal component analysis revealed contrasting patterns of change. The composition of Lippia turbinata oil shifted gradually and continuously across the thermal treatment: the relative abundance of thujone rose over time, not because the compound was being formed, but because less stable, higher-boiling terpenes degraded around it, while limonene and beta-pinene progressively declined as they oxidised into derivatives such as carveol and terpinen-4-ol. Minthostachys mollis oil behaved differently, with most of its compositional change occurring at the very beginning of the heat exposure. Pulegone, which contains a double bond, was progressively converted to the saturated ketone menthone, a transformation that reduced the pulegone-to-menthone ratio used by the group as an indicator of antioxidant potential. Crucially, however, neither pattern of change undermined the protective performance of the oils in the subsequent oxidation tests.
For the direct assay, the researchers fortified antioxidant-free commercial sunflower oil, which contains between 48 and 74 percent oxidation-prone linoleic acid, with 0.02 percent by weight of each essential oil, or with BHT at the equivalent of 200 parts per million, the maximum permitted in food. Samples were stored at 60 degrees Celsius for 28 days and monitored through an unusually comprehensive battery of indicators: conjugated dienes, peroxide value and anisidine value as chemical markers of primary and secondary oxidation; the composite TOTOX and INTOX values that integrate both stages; and the volatile aldehydes hexanal, (Z)-2-heptenal, (E,Z)-2,4-decadienal and (E,E)-2,4-decadienal, which arise from the fragmentation of oxidised linoleic acid and are directly responsible for rancid off-odours. By day 28, untreated oil showed dramatically higher values across nearly every indicator, while oils protected by the two essential oils recorded lower peroxide and anisidine values than even the BHT-treated samples, with Minthostachys mollis delivering the strongest protection overall.
Linear regression models fitted to the oxidation trajectories quantified the advantage with unusual precision. Using a peroxide value of 10 milliequivalents of oxygen per kilogram of oil as the regulatory shelf-life limit, unprotected sunflower oil reached the threshold in just 0.83 days. BHT extended this to 3.29 days, Lippia turbinata oil to 3.60 days, and Minthostachys mollis oil to 4.59 days, corresponding to shelf-life extensions of 3.92, 4.31 and 5.48 times the control. When shelf life was instead defined by a TOTOX value of 24, which better reflects the flavour-relevant secondary oxidation that makes oil unsellable, the essential oils again outperformed BHT, extending shelf life 3.60 and 4.23 times respectively compared with 3.36 times for the synthetic additive. Principal component analysis of all chemical and volatile indicators together explained 99.6 percent of the variability and placed the two essential-oil treatments closest together at the low-oxidation end of the spectrum, ahead of BHT.
The authors also address safety, an inevitable question for oils containing thujone and pulegone, both of which are regulated monoterpenes. Under European Union Regulation 1334/2008, pulegone is capped at 250 milligrams per kilogram in the strictest food category, and the tolerable daily intake is set at 0.1 milligrams per kilogram of body weight. At the 0.02 percent application rate used in the study, oil fortified with Minthostachys mollis contains roughly 63.56 milligrams of pulegone per kilogram, well below the European limit, and a 70-kilogram person would need to consume more than 100 grams of the oil daily to exceed the tolerable intake. Thujone from aromatic plants faces no food restrictions under the same regulation, and although a preliminary acceptable daily intake of 0.11 milligrams per kilogram has been proposed, the fortification level used here would require a person to consume nearly 50 grams of oil per day to approach that threshold, an implausible quantity for normal dietary habits.
The researchers conclude that Lippia turbinata and Minthostachys mollis essential oils demonstrate thermal stability that does not compromise their antioxidant activity, and a level of protection approaching or exceeding that of BHT under accelerated conditions. Both species are well suited to intensive cultivation in central Argentina, offering a renewable, biodegradable supply chain for natural antioxidants and a route away from extractive wild harvesting. The team emphasises that further work is needed across more complex food matrices, differing in moisture, polarity and sensory requirements, and in combination with different packaging systems, before industrial adoption can be fully realised. Still, the message is striking: two fragrant herbs from the Córdoba hills may help the food industry preserve freshness with molecules that return harmlessly to the biosphere rather than accumulating in it.
Subject of Research: Thermal stability and antioxidant performance of Lippia turbinata and Minthostachys mollis essential oils as renewable natural antioxidants in sunflower oil
Article Title: Thermal stability, and chemical and volatile oxidation indicators from essential oils of Lippia turbinata and Minthostachys mollis as potential natural antioxidants from renewable sources
Article References: Juncos, N. S., Navarro, B. D. V., Corradi, M. P., & Olmedo, R. H. (2026). Thermal stability, and chemical and volatile oxidation indicators from essential oils of Lippia turbinata and Minthostachys mollis as potential natural antioxidants from renewable sources. Discover Green Chemistry, 1(1), Article 20. https://doi.org/10.1007/s44509-026-00023-1
Image Credits: AI Generated
DOI: 10.1007/s44509-026-00023-1
Keywords: essential oils, natural antioxidants, lipid oxidation, Lippia turbinata, Minthostachys mollis, BHT, shelf life, thermal stability, sunflower oil, green chemistry, Thermal, stability
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Bethany Barker. (September 13, 2026). Argentine Herb Oils Outperform Synthetic Antioxidant BHT in Preserving Sunflower Oil. Scienmag. https://scienmag.com/argentine-herb-oils-outperform-synthetic-antioxidant-bht-in-preserving-sunflower-oil/
Bethany Barker. “Argentine Herb Oils Outperform Synthetic Antioxidant BHT in Preserving Sunflower Oil.” Scienmag, 13 September 2026, https://scienmag.com/argentine-herb-oils-outperform-synthetic-antioxidant-bht-in-preserving-sunflower-oil/. Accessed 13 September 2026.
Bethany Barker. “Argentine Herb Oils Outperform Synthetic Antioxidant BHT in Preserving Sunflower Oil.” Scienmag. September 13, 2026. https://scienmag.com/argentine-herb-oils-outperform-synthetic-antioxidant-bht-in-preserving-sunflower-oil/
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Tags: Argentine aromatic herbs in food preservationBHTcomparison of natural vs synthetic food antioxidantseco-friendly food additivesEssential oilsgreen chemistryherbal oil preservationlipid oxidationLippia turbinataLippia turbinata essential oilMinthostachys mollisMinthostachys mollis antioxidant propertiesnatural antioxidantsnatural food preservativesoxidative spoilage prevention in oilsplant-based antioxidantsreducing food waste with herbal oilsshelf lifestabilitysunflower oilsunflower oil shelf life extensionsustainable food storage solutionsThermalthermal stability
